Start

End

Group

I'm getting an error that says parameter 1 of mysqli_num_rows($r) should be a mysqli_result, Boolean given. Here is the applicable code:
$q = "SELECT email, username FROM users WHERE email='$e' OR username='$u'";
$r = mysqli_query($dbc,$q);
$rows = mysqli_num_rows($r); //This is where the error occurs.
Help would greatly be appreciated! Thank you.